Embodiments of the present invention relates in general to the field of cryptographic methods to implement proofs of work, such as cryptocurrency systems.
Web search engines are software systems designed to search, index, organize and rank information on the World Wide Web. The information may include web pages, images and other types of files. Search engines may also mine data available in databases or open directories. Unlike web directories, search engines maintain quasi-real-time information thanks to web crawlers (i.e., spiders), which store information about web pages retrieved from the HTML markup of the pages. These pages are retrieved by web crawlers, which follow every link on the site. The search engine then analyzes the contents of each page to determine how it should be indexed; for instance, words can be extracted from the titles, contents, headings or metatags. Data about web pages are stored in an index database for use in later queries.
Cryptocurrency systems, such as Bitcoin™, use cryptography to secure transactions. Typically, cryptocurrency systems use decentralized control (as opposed to centralized money systems) and a public ledger (e.g., Bitcoin's block chain) which records transactions. Cryptocurrencies use various timestamping schemes to avoid the need for a trusted third party to timestamp transactions added to the blockchain ledger. The first timestamping scheme invented was the proof-of-work (PoW) scheme. The most widely used PoW schemes are based on the so-called SHA-256 algorithm, introduced by Bitcoin™, and scrypt. Other hashing algorithms used for PoW include Blake, SHA-3, and X11. Some cryptocurrency systems use a combined proof-of-work/proof-of-stake scheme. The Proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus by requesting users to show ownership of a certain amount of currency. It differs from PoW systems that run resource-intensive hashing algorithms to validate electronic transactions and to generate new currency units (i.e., mining or coin-minting).